Holler for a Spark: Energy through Sound!

The creation of sound has always been a factor in human development, with the first signs of music being in human culture as early as 40 000 years ago (National Museum of Natural History 2024). The application of sounds in the daily life of a person seems psychologically beneficial but resourcefully useless; that is unless there could be a way to harvest its energy.

The concept of using sound as a renewable source of energy has been developing for quite a while now, since the vibrations they produce can be harvested with the help of piezoelectric materials (Ahmed, Mir, and Banerjee 2017). These materials have a crucial role in being able to harvest any type of mechanical energy, since their response to a strain of that type is electrical polarization, which can be useful to conduct electricity through the material (Xu et al. 2018). The main purpose of piezoelectricity in this scenario would be to use it as a conductor, and use the frequencies to create a net charge in the material (Just Energy 2021; Figure 1). Something this abstract would evidently face difficulties, one of them being the storage of such an energy. A method known as coherent virtual absorption was brought to light, in which the way sound waves interact with certain materials was altered to make it suitable for storage. Another time a patent was filed to make storage of sound energy long term, particularly useful in remote areas. All these ideas are an indication that scientists are finding diverse and useful ways to accomplish this task (Tara Energy 2021). Experiments being run on this technology portray the possibility of it being available for commercial use for locations that have normal human activity, such as a classroom or a busy street, because of it being viable in the 35-100 decibel range (Fang et al. 2017).

A tool this sound could have numerous applications, and more methods of implementing it are brought to light as time goes on, with suggestions of it being useful for not only energy production in and of itself, but also the betterment of other methods. Etched stops in solar cells are used to limit performance degradation and help reuse the substrate of the GaAs (gallium arsenide) cell, except this process takes hours and requires for the substrate to be polished afterwards. An acoustically spalled wafer is something that can be used to speed up this process, it being a wafer of materials being fractured (spalled) in a frequency controlled environment (acoustic), which helps limit the severity of the fractures. The substrate can be taken off way easier, and the ultimate result does not require for the material to be polished (Hicks 2023; Schulte et al. 2023; Figure 2).

These advancements in renewable resource technologies are all extremely exciting, but the application of sound as energy produces way less power than someone could imagine. The amount of sunlight hitting a specific spot on the ground is around 680 watts per meter squared, which is orders of magnitude more than what energy sound could generate; the distribution of sound over an expanded area of space leaves for it to have a hundredth of watts per meter squared (Jensen 2011). Nevertheless, advancements made by scientists suggest that this is not an idea to be abandoned just yet, for this is a time where humans need energy the most, and any way of acquiring this energy, no matter how small, would turn out to be an incredible resource in the long run.

Works cited

Ahmed, Riaz, Fariha Mir, and Sourav Banerjee. 2017. “A Review on Energy Harvesting Approaches for Renewable Energies from Ambient Vibrations and Acoustic Waves Using Piezoelectricity.” Smart Materials and Structures 26 (8): 085031. https://doi.org/10.1088/1361-665X/aa7bfb.

Fang, Liew Hui, Syed Idris Syed Hassan, Rosemizi Abd Rahim, Muzamir Isa, and Baharuddin bin Ismail. 2017. “Exploring Piezoelectric for Sound Wave as Energy Harvester.” Energy Procedia, 8th International Conference on Applied Energy, ICAE2016, 8-11 October 2016, Beijing, China, 105 (May):459–66. https://doi.org/10.1016/j.egypro.2017.03.341.

Hicks, Wayne. 2023. “NREL Puts Sound Waves to Test in Making Solar Cells Cheaper.” July 19, 2023. https://www.nrel.gov/news/program/2023/nrel-puts-sound-waves-to-test-in-making-solar-cells-cheaper.html.

Jensen, Sarah. 2011. “MIT School of Engineering | » Can Sound Be Converted to Useful Energy?” Mit Engineering (blog). November 15, 2011. https://engineering.mit.edu/engage/ask-an-engineer/can-sound-be-converted-to-useful-energy/.

Just Energy. 2021. “Sound Energy: Everything You Need to Know.” Just Energy. August 28, 2021. https://justenergy.com/blog/sound-energy-everything-you-need-to-know/.

National Museum of Natural History. 2024. “Art & Music | The Smithsonian Institution’s Human Origins Program.” January 3, 2024. https://humanorigins.si.edu/evidence/behavior/art-music.

Schulte, Kevin L., Steve W. Johnston, Anna K. Braun, Jacob T. Boyer, Anica N. Neumann, William E. McMahon, Michelle Young, et al. 2023. “GaAs Solar Cells Grown on Acoustically Spalled GaAs Substrates with 27% Efficiency.” Joule 7 (7): 1529–42. https://doi.org/10.1016/j.joule.2023.05.019.

Tara Energy. 2021. “Sound Energy: Beginner’s Guide to This Energy Source.” Tara Energy. September 1, 2021. https://taraenergy.com/blog/sound-energy-beginners-guide/.Xu, Runzhang, Xiaolong Zou, Bilu Liu, and Hui-Ming Cheng. 2018. “Computational Design and Property Predictions for Two-Dimensional Nanostructures.” Materials Today 21 (4): 391–418. https://doi.org/10.1016/j.mattod.2018.03.003.